Good morning, I hope I can help you.
This fault is usually caused by the alternator or a wiring fault at the alternator.
If you have new alternator and fault is occurring then either the alternator is faulty or its wiring is.
The only other possibility is a faulty ignition switch but if the engne starts ok and you are able to switch it off with the key then it wont be the switch. When the switch goes faulty you usually find you have to stall the engine to switch it off.
All I can say is that I was close. Battery connections and alternator connections are basically the same but at different ends of the connection.